1. Field of the Invention
The present invention relates to a technology for dynamically setting the communication path of an optical communication network system having a priority control function. The present invention can be applied to an optical communication network system for the Internet, for example.
2. Description of Related Art
The communication network can be divided into controllable domains which the maintenance administrator can control and manage, and external domains which the administrator cannot control and manage. When a plurality of communication paths are constructed in a controllable domain, it is desirable to allocate larger the line capacity of the communication path of which the data transfer volume is large, and to allocate smaller the line capacity of the communication path of which the data transfer volume is small. Resources can be effectively used by setting paths corresponding to the dispersion of traffic in the communication system. However in the case of an IP communication network, such as the Internet, where traffic changes are very radical, it is difficult to construct a communication path estimating the volume of traffic in advance. Therefore it is desirable to construct a communication network system such that the communication paths can be dynamically changed according to the changes of the traffic distribution. Following references I and II are known as documents proposing a dynamic communication network system.
I. Japanese Patent Laid-Open Publication No. 2000-232483, and
II. “An Algorithm to Reconfigure Logical Topologies in Reliable WDM Networks” by Ishida and two others, Technical Report of IEICE 2002-9, April 2002, pp. 49-54.
In the communication network system of the reference I, the packet flow rate monitoring means PFM disposed in each packet exchange PEX monitors the traffic volume. The network management center NMC sets a new communication path in a block where traffic is high or deletes a communication path in a block where traffic is small based on the monitoring result of each packet flow rate monitoring means PFM.
In the reference II, a technology for decreasing the loss of packets when a current communication path is deleted and a new communication path is set is proposed.
However, a method for the network management center NMC to perform all the settings and cancellation of communication paths is used with the technology proposed in the reference I, so the entire system stops if the network management center NMC fails when a new path is attempted to be setup. Also to decrease the contention of the network management center NMC and network for control, the processing capability and communication capability must be increased, which increases cost.
According to the technology of reference II, a communication path to shelter traffic is established separately, for which resources are necessary.